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WOLF BLITZER, CNN ANCHOR: One of the little publicized stories in the immediate aftermath of 9/11 was how the Bush administration helped Saudi citizens leave the United States, including relatives of Osama bin Laden and the Saudi royal family. Writer Craig Unger of "Vanity Fair" says there's much more to this than meets the eye, the details of which appeared in the October issue of "Vanity Fair." The magazine article is just part Craig Unger's upcoming book, "House of Bush, House of Saud," due to be released next spring. He's joining us now live from New York.

It is a complex relationship between these two families, but give us the gist. What is your worst case fear, based on the quick exodus, if you will, of relatives of Osama bin Laden, and Saudi royal family members in the United States in the immediate aftermath of 9/11, even though 15 of the 19 hijackers were Saudis?

CRAIG UNGER, "VANITY FAIR": Right. Well, I think the key question is, why did the Saudis get a pass? That is, immediately after any murder, whether it is a commonplace murder or a horrible national tragedy like 9/11, one of the first things you would do would be to talk to the friends and relatives of the perpetrator. In this case, Osama bin Laden. And 140 Saudis, including roughly 24 members of the bin Laden family, left in the days following that without being seriously interrogated.

So I think one of the key questions that people really haven't explored is that you have an unprecedented relationship in the history of the White House. Never before have you had one president, much less two in the same family who have been so close to the ruling family of another foreign power; in this case, the House of Saud.

BLITZER: And how does that impact U.S. policy today if, in fact, there's this incredibly close relationship?

UNGER: Well, it's a very complex relationship. And, yes, it is close, and there are very many delicate issues. We have oil there, the Saudis have been useful in terms of regional conflict in the area.

But when it comes to 9/11, here we have a real war on terror going on. And we sent 135,000 troops to Iraq, which really had nothing to do with 9/11. Why did we let the Saudis get a pass on this? Why weren't they interrogated, why weren't they interviewed? What role have they played in terrorism?

BLITZER: Well, what is the answer? What do you believe the answer is? UNGER: Well, we do know that 15 out of the 19 hijackers were Saudis. We also know that Saudi Arabia is a theocratic monarchy. It's fostered a breeding ground for terrorism.

And in the last year, there have been a lot of revelations that have linked higher-ups in the royal family to -- unwittingly or not -- to terrorism. So the question is, why has the Bush administration been so soft? And I think it will be very interesting to see whether or not the Democrats pick it up in the presidential campaign coming up.

BLITZER: When the Saudis got a pass, as you say, to leave the country in the days immediately after 9/11, they had some chartered flights that were allowed to take off. Did the U.S. government know at that point that 15 of the 19 hijackers were in fact Saudi nationals?

UNGER: Absolutely. They knew by September 12th that 15 of them were Saudi nationals. And it was a nightmare for Prince Bandar (ph), who is the Saudi ambassador to the United States. And he started orchestrating a big PR blitz.

BLITZER: And he managed to get them out. I guess the Saudis concern, from their point of view, was there could be retaliation, there could be anger and even violence directed at these Saudis given the publicity that was then coming out, that so many of the hijackers were Saudis. From their perspective, they wanted these people, the relatives of Osama bin Laden, in particular, to get out before anyone could do harm to them.

UNGER: Well, that certainly was their stated concern, and I can understand that. At the same time, I've never seen any real reports of Americans actually threatening the Saudis. And at a time like that, I think we have to race the question about, what about America's national security? Here we've gone through a tragedy; don't the victims of 9/11 deserve a serious investigation?

BLITZER: As you look at the Saudi attitude right now in the aftermath of that terrorist bombing in Riyadh a few months back, they seem to be becoming much more aggressive in looking for these terrorists and much more cooperative with the FBI and other U.S. law enforcement agencies in trying to find the source of this problem.

UNGER: Well, that is certainly true, but you are referring to the May 12th bombing in 2003. Supposedly -- and President Bush said the Saudis were cooperative immediately after 9/11. What about the intervening year and a half? Why -- if they are so cooperative now, what was going on in the immediate year and a half right after 9/11?

BLITZER: What -- so what's the answer?

UNGER: Well, I think the Saudis have not been nearly so cooperative. And this goes back to the early years of the Clinton administration when the bombing started around '95 in Saudi Arabia, killing Americans in Riyadh. The Saudi Arabian national guard headquarters, Americans were killed there. They were killed in the Khobar Tower bombings.

And in each case, Saudis were executed at times without being allowed to be interviewed by FBI officials. So there's been a history of not being quite so cooperative as they have said they have been.

BLITZER: Craig Unger, a reporter, writer for "Vanity Fair." He's got a new book coming out next year: "House of Bush, House of Saud." I suspect the house of Bush and the house of Saud won't be happy with your book, Craig. But thanks very much for joining us.